Enteric bacteria such as Salmonella and Escherichia coli can cause food-borne illness in humans due to ingestion of contaminated food products. The economic and health consequences of contaminated livestock increase the importance of finding an inexpensive yet effective method of reducing or eliminating food-borne illness. Concern regarding the overuse of antibiotics has lead to a search for alternative mechanisms to combat livestock-related infection.
Bacteria resistant to antibiotics are a threat to human and animal health. New classes of antibiotics have not been discovered in the past 30 years. Furthermore, antimicrobial usage in animals is being restricted in order to protect the public health. Concurrently, changes in social awareness and concerns regarding food safety have increased the need for reduced levels of Salmonella in pigs and other livestock.
Previous studies reported that the culture positive rate of Salmonella in market weight pigs gradually increases from farm to lariage, and ultimately to slaughterhouse. The sources of Salmonella contamination in pigs includes environments (transportation vehicles, holding areas, etc.), active Salmonella shedding pigs, and recurrent Salmonella shedding among carriers because of stress during transport or delivery. Healthy pigs become Salmonella culture positive in tissue samples within as few as three hours after infection resulting from exposure to Salmonella infected pigs. No matter what the sources of Salmonella infection into market weight pigs, the rapid dissemination of Salmonella in pigs prior to slaughter is an important risk factor in pork product contamination.
Bacteriophage resemble human and animal viruses in a number of ways. For example, viruses infect specific cell types and can cause extensive damage to the infected cells. In animals, this can lead to the production of diseases. Likewise, phages have specific bacterial targets and can cause extensive damage to the bacteria. Lytic bacteriophage are a particularly efficient killing machine for bacterial cells. Lytic bacteriophage initially contact their hosts through specific receptors in their tail followed by injection of their DNA into the host bacterial cell. Like a xe2x80x9cTrojan Horse,xe2x80x9d once inside the cell they direct the production of quantities of progeny phage that are released when the bacterium is lysed and killed by the phage. Lytic phages continue to proliferate in an animal as long as bacteria are present to be infected by the phage.
Experimentally, phage have been shown to reduce diarrhea and the numbers of Escherichia coli in the intestine of piglets. Smith, H. W. and Huggins, M. B., Effectiveness in Treating Experimental Escherichia coli Diarrhea in Calves, Piglets and Lambs, Journal of General Microbiology 129:2659-75 (1983). Phages lytic for Salmonella typhimurium were found to reduce the levels of Salmonella in both the digestive tract and liver of day-old chicks. Berchieri et al., The Activity In The Chicken Alimentary Tract Of Bacteriophages Lytic For Salmonella typhimurium, Res. Microbiol., 142:541-549 (1991). Research publications and review articles regarding phage have identified various problems, misconceptions, and pitfalls associated with their use as therapeutics. Of particular concern is the selection of resistant bacteria through long-term use of bacteriophage treatment. Resistant bacteria may be a more significant health threat than the initial disease if antibiotics or other bacteriophage are not available to treat the resistant organisms.
Because the reduction of Salmonella in livestock prior to slaughter can reduce the prevalence of food-borne human salmonellosis, there has been much interest in developing pre-harvest reduction strategies against Salmonella. Despite many studies, an effective strategy to control Salmonella in livestock has not previously been found.
This invention provides compositions comprising Felix 0-1 Phage (F01 phage) in an acceptable carrier and methods of using the compositions to reduce the amount of Salmonella in livestock and meat products. The present inventors have found that the F01 phage significantly reduces Salmonella in livestock. One embodiment of the invention provides a composition for reducing the amount of Salmonella in a livestock animal comprising a Salmonella reducing effect amount of the F01 phage in an acceptable carrier.
Also provided herein are methods of reducing the amount of Salmonella in a swine prior to shipment by administering a composition containing F01 phage, in an acceptable carrier to swine from about 24 hours to less than about 3 hours prior to harvest of the swine, in an amount effective to reduce the amount of Salmonella in the swine.
Additional embodiments of the present invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned through the practice of the invention. The objects and advantages of the invention will be attained by means of the instrumentalities and combinations particularly pointed out in the appended claims.